Investigations on age-related changes in ovaries of Drosophila melanogaster showed that only egg laying capacity and hatchability decreased with the age of flies. The total ovarian protein, yolk protein as well as specific activities of acid phosphatase and aldehyde oxidase remained unaltered with age. Unlike the ovary, acid phosphatase activity in the carcass increased with age, suggesting tissue specific age-related changes. Ovaries from short lived mutant (apterous4) flies when transplanted into wild type flies survived at least 10 days (4 days longer than the life span of ap4 flies) and even produced morphologically normal oocytes. Other mutant stocks with reduced life span (e.g., lon-) are being constructed to test the concept of tissue autonomy in aging. Preliminary data from transplantation studies suggest that the age of the host affects the rate of egg development in the transplanted ovary. Using an antivelline antibody the rate of vitellogenin production by fat body from flies of diverse ages and the effects of insect hormones are being studied. These studies are aimed at determining the extent to which aging of some tissues is dependent on the senescence of other tissues in the organism.